


Dirty Little Secret

by p00rb01



Category: Undertale (Video Game)
Genre: Alternate Universe - Stripper/Exotic Dancer, Alternate Universe - Underlust, Implied/Referenced Incest, Incest, Lust, M/M, Masturbation, NSFW, Pining, Sad, Sad Porn, Sibling Incest, Strippers & Strip Clubs, UnderLust Mettaton - Freeform, Underlust Grillby - Freeform, Underlust Papyrus - Freeform, Underlust Sans - Freeform, Unrequited, Unrequited Love, Unrequited Lust, lust!papyrus, lust!sans - Freeform
Language: English
Status: Completed
Published: 2018-01-04
Updated: 2018-01-04
Packaged: 2019-02-28 05:59:12
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,963
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13265175
Author URL: https://archiveofourown.org/users/p00rb01/pseuds/p00rb01
Summary: After Papyrus misses Sans' show for the millionth time to be with Mettaton, it wares on the poor skeleton. Wanting nothing more than to come home to his loving brother and forget about these jealous feelings rising up inside of him, Sans walks in on something he wish he hadn't.





	Dirty Little Secret

Loud booming music radiated out of the open club doors, a line of monsters outside waiting to get in. Some peeking around Greater Dog to try and see inside, dying to get a preview of what everyone was there for. Inside, in the middle of the huge obnoxious crowd of monsters, was a small scantily clad skeleton. This being a nightly occurrence, it wasn’t much of a shock to the town that Grillby’s was booming as usual. The purple heart eyed skeleton was doing his turn on the catwalk, sleeveless open parka flowing with him with each spin or bop. Showing off a lot of bone as his jacket didn’t cover much about him and he was lacking a shirt. This skeleton was Sans. The clubs most popular dancer. He raked in almost all of the town each night he preformed. He was working almost nightly at this rate, but he needed to afford his house and younger brothers needs so he wasn’t about to complain.

The dancer made his way down to the pole, wrapping a boney leg around it to twirl. His purple panties not restricting his movements in the least, clinging to his pelvis, a small purple glow coming from his crotch area. After gripping the pole with a slender hand he hoisted himself upside down, reinforcing himself by moving his leg to wrap further up the pole. His other leg high up in the air, phalanges pointed to give himself a elegant look. Sans tilted his head back toward the crowd, right eye closed, he summoned a glowing purple tongue. Allowing the appendage to slide out from behind his grin, oozing with lust. His raised leg slowly lowered down toward his skull, keeping straight as he did so. Jacket hanging down passed his skull now, showing off all of his delicate ribs and spine. The crowd went crazy, cheering and howling.

Sans’ spine bent backwards more, leg lowering along with him in sync. Once he got to where he could hold onto the pole with both of his hands he let go of the top of the pole. Allowing his other leg to swing down, letting him spin and straddle the cold metal. Spinning till he was then sitting back onto the floor. Lustful monster reached out for the purple skeleton as he was in reach, causing a chuckle to pass his mouth. Hopeful purple eyes scanned the crowd, searching for a certain familiar face. A small frown tugged at the corners of his mouth in it’s absence. But quickly snapped out of it once the sound of the DJ calling the end of his act filled the room. He quickly spun back around the pole to stand up, back to the crowd and against the pole as he did a last dip down to the floor. Popping back up with ease, he blew a kiss to the crowd, a quick wink for them and he was off. Once he was out of view from the customers and backstage, he sighed, eyes saddening.

His brother wasn’t here. He had been missing his performances for his dates with his new boyfriend Mettaton lately. And while the older skeleton was happy for his brother. He couldn’t help the cold sinking feeling in his soul when the robot was chosen over him. His eyes casted down to the ground, pulling his jacket around himself as he made his way back to the dressing room. He kept his head down as he passed others, flashing a small fake smile at them when they congratulated him on his act, thanking them back. But just trying to quickly toss on his clothes and leave so he could be alone. He pulled on his tank top and shimmied into his jeans, the glowing in his pants now long gone. Dipping out the dressing room, before leaving he gave a small genuine smile toward the bartender Grillby. Waving bye like he did every night, once it was returned he left out the back of the club.

The frown returned, shoving his chilly hands in his parka pockets, a shiver ringing through him when he was hit with a cold winter breeze. Only succeeding in making him feel even more alone. If Papyrus was here he would’ve brought him a sweater and distracted him from the cold by chattering on about his day. But right now it was only Sans and his thoughts while he walked back home. The pounding music of the club disappeared in the distance the further he got from it. Only sound now being the rushing wind and crunch of snow beneath his shoes with each step. Sans hiked up his shoulder so the fur from his hood would brush along his cheeks, at least a small feeling of warmth. His head filling with sad thoughts of going home to an empty house again, not eating and just passing out on the couch waiting for his brother to come home. To only have him sneak in early in the morning and try not to wake him. It did every time though. He just pretended to be asleep so it wouldn’t make Papyrus feel bad.

Was it wrong for Sans to be so upset by them dating? Just being chosen last stung. Especially when the other was Sans’ whole world. The fact that the sentiment wasn’t returned hurt. It wasn’t like he disliked Mettaton though! No! He was a nice guy. A little shy and dorky but there was nothing to dislike about the guy. But for some reason a pain would creep it's way into his chest when he’d see them together. He didn’t try to dwell on it too much. He knew what that feeling meant. He use to feel that way when he would see Grillby flirting with someone back when they had a thing going on. But he didn’t want to think about the fact that it felt the same. The fact that it meant he had feelings for his younger brother that weren’t… brotherly. God, he was fucked up. He cringed at the thought. Papyrus would hate him and never want to see him again. He’d get to see the other even less than he did now! He couldn’t handle that. Sans would rather see the taller skeleton occasionally and be in pain than never at all and be absolutely crushed. He didn’t think he could handle that.

He walked up to their porch, tapping the front of his shoes on the cement to shake off the snow as he fished the keys out from his pockets. He heard something inside and paused. Oh. Was Papyrus home already? Might’ve just gotten done hanging out with Mettaton. That’s good! Maybe they can actually hang out. That brought a smile to his face as he unlocked the door, just walking in “pap! hey! how was the-,” He froze as he saw his brother and Mettaton on the couch, tongues down each others throats. His soul sunk at the sight. Now it was no secret Papyrus was promiscuous. Everyone was in this world. They couldn’t help it. But his brother had always made it a point to never do anything like that at home because Sans was there and that’d ‘be rude.’ So come to think of it. Sans has never even see Papyrus kiss someone before. And from what he just saw. It didn’t feel too great… The hearts in his eyes disappeared in an instant, leaving only hollow empty sockets.

The two jumped quickly away from each other, Mettaton quickly hiding his face in his hands in embarrassment. His glasses squishing up awkwardly against his face. The sweater clad skeleton’s cheekbones flushed a bright vibrant pink “S-Sans! Um! I-I Forgot You Got Off Early Tonight! Um-I’m Sorry. We Should’ve Gone To My-”

Sans held up a hand, fake grin plastered on his face “nah-it’s cool. don’t let me stop ya, bro. heh.” He pushed the door shut a little roughly with his foot “have fun. i’m hittin’ the hay. long day.” He held back tears as he tried to dart toward the stairs.

A frown tugged at the corners of Papyrus’ mouth, jumping up to block his path “Brother? Wait- Are You Okay? Did Something Happen?” This caused Mettaton to peek up at them in worry, eyes following them both.

Sans kept trying to step around him, not wanting to break in front of them both “no. just tired. can i-just-,” He clenched his fists, purple tears welling up in the corner of his sockets, causing his purple heart pupils to return but with a crack through them as he looking up desperately at Papyrus “can i PLEASE just go to my room, papyrus?!” he sobbed, tears rolling down his cheeks when everything just finally was a little too much for him. He hung his head, gripping at his skull. The smaller skeleton’s shoulders shook as he cried “p-please.. please, pap..”

Papyrus’ sockets widened, hands up, as his brother not only snapped at him but started breaking down. Not sure if he should hug his brother or just move aside and let him. But he swallowed and quickly looked toward his boyfriend who was already getting up and mouthing to him that he was going to go with a small reassuring smile and a wave. The taller skeleton’s eyes softened, smiling back with a nod toward the other as he quietly left. He had such a great understanding boyfriend. Once Mettaton was gone he wrapped his arms around Sans, gently rubbing his hand up and down the back of his spine soothingly. Shooshing the other, “Sans.. It’s Just You And Me Now.. What's Wrong?”

Sans let out a pitiful whimper, burying his face into his brothers tight sweater with a shake, “h-heh...w-why do you have to be so great?” He laughed sadly, bringing his hands up to rub at his damp eye sockets, “it’s nothin’, pap. really.” His voice cracked, flashing his brother a big grin. “i’m just having a bad day. didn’t mean to ruin your date, bud.”

Papyrus frowned down at his older brother, not falling for the false smile. “Sans, You Didn’t Ruin Anything. You’re My Brother And You’re Upset. Mettaton Understands.”

Sans shook his head, trying to break free from the other skeleton’s grasp, “i’m not upset, really. i’m fine.”

“Sans, You’re Obviously Upse-”

Sans laughed, cutting him off as he tried to pull back again, “i’m really no-”

“Don’t Lie To Me!”

“i’m not lyi-”

Papyrus huffed “Sans!” his grip on him tightened.

The shorter brother froze under his hold, smile dropping as he peeked back up at him. Papyrus’ gaze softened once he finally got his brother to stop, grip loosening. Staring to gently rub the others upper arms with a gentle flick of his thumb, “I Know When You’re Hurt, Brother.. Your Eyes Give You Away.... They’re Broken..” He brought a hand up to gently rub the tears beside Sans’ eyes away but Sans cringed away from the touch, remembering why he suppressed his pupils in the first place. Trying his damndest to not show his eyes to his brother right then. Knowing they were still that way. Papyrus sighed, rejected hand falling back down to his side. “Alright, Sans. If You Don’t Want To Talk About It, I Am Not Going To Force You.. But-” He crouched to get into Sans’ line of sight, desperate to make eye contact “I’d Really Love It If You Did Decide To Talk To Me About It.. I’m Here For You, Brother. I Love You. I’ll Always Be Here For You. You Know That, Right?”

Sans’ bit back the want to bring up that fact that no Papyrus hadn’t been there for him lately and how he was having such a hard time knowing all that right now. But he just couldn’t bring himself to. Papyrus cared so much about him. It wasn’t his fault he was happy and just doing what people do when they date. Sans was the fucked up one. Even more so for making Papyrus worry about him. God he was such a dick.. Guilt made it's way into the pit of his soul so he nodded back, trying hard to keep up his weak smile, “i love you too, bro… but... this ain’t somethin’ i’m really wanting to talk about.. but i really do appreciate you caring.” He wrapped his small arms around the other. Papyrus immediately brightened up at that, hugging Sans tightly.

“Well… Alright. But Swear That If You Need Me You’ll Come Get Me, Okay?” He gave him one last tight squeeze, wagging a finger at the other.

Sans nodded, letting out a weak laugh, “yeah...i swear.” He lied

Papyrus pulled back, smiling brightly down at his brother, “Alright! Then Go On Up To Bed And Get Some Sleep. I’ll Leave Your Dinner In The Microwave For When You’re Feeling Up To It.”

Sans smiled a little wider at him, hand on the railing of the stairs as he started making his way up toward his room. “thanks, buddy..” Turning toward his room, he swallowed. No. He couldn’t tell Papyrus about his feelings. He was too good. He deserved better. And he has Mettaton. He already has better. He blinked down to the hall over the railing at Papyrus as he other made his way into the kitchen, tying on his apron with a smile. Sans’ eyes softened. Yeah. For Papyrus he could deal with the hurt. He made his way into his messy room, closing the door behind him. He shimmied off his wet sneakers, jumping into bed. His hands snaked under his pillow to pull out a long pink sweater. Papyrus’ sweater. He had stolen it from the laundry a few weeks back when he had begun missing the taller skeleton. He just wore it at first for comfort and a joke but now it was like he needed it to sleep. Especially if the other was gone. Or it had been a particularly rough day like today. Bringing the soft fabric up his face, he was surrounded by that intoxicating smell. Like strong mens cologne with a hint of flowers and spaghetti. He started feeling the stinging prick of tears reach his heartbroken eyes once again. 

Fuck. He really was sick. Feeling his magic bottle up in his pelvis region, he cursed the never ending heat they were all under. He couldn’t help it. Today had just been too much. And it’s not like Papyrus had to know. He let his eyes slowly slide shut, imagining it was Papyrus he was curling up to instead of just this sweater. All he could smell now was his brother, pressing the cloth further against his face. Feeling surrounded in him. He hesitated but slowly dipped a hand down himself to his waist band. Popping open the top button of his jeans, shoving them down just far enough to be able to reach his dripping entrance. He muffled a whimper into the shirt as he felt the cool breeze touch him. Normally at times like this he would hop on over to grillby’s or another monsters house to take care of it. But right now he just really wanted to pretend for just awhile that Papyrus was his and not Mettaton’s. That he loved him back.

He began to rub his rough phalanges over the sensitive nub, shuddering. “aah~” he moaned into the cloth to keep his brother from hearing. But from the sounds of clanging pots and running water coming from downstairs said he probably wouldn’t be able to hear otherwise. He let himself fade into his imagination. His brother over him, hands all over him. Taking his time but being loving and romantic like he always was with anyone he took a liking to. His breathing picked up along with his hand, dipping a few fingers into his aching hole. Papyrus lining up and slowly entering him, eventually picking up the pace. Making sure to kiss him all over and let Sans know how beautiful and amazing he was. He bucked up against his hand, gripping the sweater tighter. God he wanted that. Tears escaped the corners of his eyes sockets as he continued, shaking as he got closer and closer to cumming. Imagining his brother encouraging him to completion, assuring him that they’d cum together. That he’d fill Sans up to the hilt. Making sure he was nice and full with him.

“f-fuuu~ck, paps-papyrus…” He gasped at the thoughts. “please-fuck yes” He rolled onto his back, pants wiggled down to his ankles now along with his panties, sweater over his face as he bucked fruitlessly into the air to try to get more of something. Anything. He wanted the real Papyrus. He came with a loud moan of his younger brothers name into said brother sweater. Ribs rising and falling as he came down from his lust filled high. Slowly moving the sweater down off of his face, removing his fingers from inside of himself. The purple skeletons pelvis falling back down to the bed. Legs still spread wide tiredly, purple juices splattered his legs and sheets. He could feel the tears returning, now feeling guilting for doing what he just did. He turned to his side, weakly pulling his covers fully over himself with a sob. Curling up under the blanket, hugging the sweater tightly. Crying quietly to himself with a broken smile. He could deal with it all in silence and not let Papyrus worry.

It’s what big brothers do. Protect their younger siblings from bad things.

In this case. Himself.

It was better if no one ever knew.

It was better if this just all stayed his dirty little secret.

**Author's Note:**

> Hey, guys! Haven't written anything in awhile. Sorry this sucks I really just wanted to write something with Lust!Sans. Maybe I'll write more in the future. Hope you liked it!


End file.
